Networks using repeaters for re-transmision of information are well-known. In wireless networks such as cellular wireless networks, it is known to provide repeaters for signals transmitted from base transceiver stations. In such arrangements the radio signal transmitted by a base transceiver station is received by a repeater and is re-transmitted by the repeater. A base transceiver station having a repeater associated there with is known as a donor base transceiver station. A donor base transceiver station may be asscociated with a plurality of repeaters.
The existence of the repeaters in the cellular network leads to problems for a mobile station (MS) location calculation utilizing the network information (such as base transceiver station (BTS) coordinates).
In a normal network there is no direct indication in a signal as to whether it has been transmitted directly by the donor BTS or by an associated repeater. Any signal from a repeater ‘looks’ like it has simply come from the associated donor BTS.
Thus the signals obtained by the MS give no indication as to whether they are from the donor BTS or an associated repeater. As such, reliable and accurate determination of the MS location based on such measurements on signals is difficult. Whilst the unit calculating the MS location knows the location of the donor BTS and associated repeaters, it does not know from which one the measurements were obtained.
It is therefore an aim of the present invention to provide a technique suitable for determining the path traveled by a signal transmitted using a donor BTS, and thereby determine the point of transmission of the signal measured by MS.
It is a further aim of the present invention to use the path determination to provide an accurate location estimate for a mobile station receiving signals originating from the donor BTS.